Hierarchical Ni₃S₂nanorod@nanosheet arrays on Ni foam for high-performance supercapacitor

We successfully designed and prepared hierarchical Ni₃S₂nanorod@nanosheet arrays on three-dimensional Ni foam via facile hydrothermal sulfuration. We conducted a series of time- and temperature-dependent experiments to determine the Ostwald ripening process of hierarchical Ni₃S₂nanorod@nanosheet arrays. The rationally hierarchical architecture creates an excellent supercapacitor electrode for Ni₃S₂nanorod@nanosheet arrays. The areal capacitance of this array reaches 5.5 F cm^-2at 2 mA cm^-2, which is much higher than that of Ni₃S₂nanosheet arrays (1.5 F cm^-2). The corresponding asymmetric supercapacitor exhibits a wide potential window of 1.6 V and energy density up to 1.0 Wh cm^-2when the proposed array is utilized as the positive electrode with activated carbon as the negative electrode. This electrochemical performance enhancement is attributable to the hierarchical structure and synergistic cooperation of macroporous Ni foam and well-aligned Ni₃S₂nanorod@nanosheet arrays. Our results represent a promising approach to the preparation of hierarchical nanorod@nanosheet arrays as high-performing electrochemical capacitors.